<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[code_aliu的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/code_aliu</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; code_aliu]]></copyright><item><title><![CDATA[SQL查询出的字段如果为null，赋默认值]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129981769</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129981769</guid><author>code_aliu</author><pubDate>Thu, 06 Apr 2023 09:16:12 +0800</pubDate><description><![CDATA[si.screen_status, sp.student_name, IFNULL(srp.va_data,0) as va_data, IFNULL(srp.se_data,0) as se_data,
        IFNULL(srp.al_data,0) as al_data,IFNULL(srp.img_data,0) as img_data]]></description><category></category></item><item><title><![CDATA[校验身高体重正则]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129981758</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129981758</guid><author>code_aliu</author><pubDate>Thu, 06 Apr 2023 09:12:48 +0800</pubDate><description><![CDATA[体重：var weightReg = /^(0(\.\d{1}){0,1}|[1-8]\d{1,3}(\.\d{1}){0,1}|9\d{1,2}(\.\d{1}){0,1}|999(\.0){0,1}|.{0})$/;身高：var heightReg = /^(0{1}|[1-9]\d{0,3}|.{0})$/;]]></description><category></category></item><item><title><![CDATA[Redis的set集合]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129838719</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129838719</guid><author>code_aliu</author><pubDate>Wed, 29 Mar 2023 15:54:13 +0800</pubDate><description><![CDATA[redis的set集合]]></description><category></category></item><item><title><![CDATA[HVALS的应用]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129801123</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129801123</guid><author>code_aliu</author><pubDate>Mon, 27 Mar 2023 18:41:25 +0800</pubDate><description><![CDATA[redis]]></description><category></category></item><item><title><![CDATA[过滤器和拦截器的区别]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129729507</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129729507</guid><author>code_aliu</author><pubDate>Thu, 23 Mar 2023 14:01:28 +0800</pubDate><description><![CDATA[过滤器和拦截器的区别]]></description><category></category></item><item><title><![CDATA[mysql 查询数据时，自动为结果编上序号]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/129727427</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/129727427</guid><author>code_aliu</author><pubDate>Thu, 23 Mar 2023 11:29:17 +0800</pubDate><description><![CDATA[mysql 查询数据时，自动为结果编上序号]]></description><category></category></item><item><title><![CDATA[同源策略--origin--web文档的来源]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/128639042</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/128639042</guid><author>code_aliu</author><pubDate>Wed, 11 Jan 2023 09:06:04 +0800</pubDate><description><![CDATA[同源策略---讲web文档之间的安全传输]]></description><category></category></item><item><title><![CDATA[MySQL建表之后增加主键和外键（删除）]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/126290715</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/126290715</guid><author>code_aliu</author><pubDate>Thu, 11 Aug 2022 18:18:34 +0800</pubDate><description><![CDATA[MySQL建表之后增加主键和外键（删除）]]></description><category></category></item><item><title><![CDATA[删除自增的主键]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/126241917</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/126241917</guid><author>code_aliu</author><pubDate>Tue, 09 Aug 2022 10:14:44 +0800</pubDate><description><![CDATA[删除自增的主键]]></description><category></category></item><item><title><![CDATA[java - metaData.getPrimaryKeys()]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/126233152</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/126233152</guid><author>code_aliu</author><pubDate>Mon, 08 Aug 2022 18:21:42 +0800</pubDate><description><![CDATA[getPrimaryKey和getImportedKey的参数设置问题（按自己需求指定参数）]]></description><category></category></item><item><title><![CDATA[RowKey设计——避免使用时序或单调(递减/递增)行键]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/126161944</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/126161944</guid><author>code_aliu</author><pubDate>Thu, 04 Aug 2022 16:27:57 +0800</pubDate><description><![CDATA[hbase的RowKey设计原则]]></description><category></category></item><item><title><![CDATA[ClusterId read in ZooKeeper is null 处理]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/126103897</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/126103897</guid><author>code_aliu</author><pubDate>Mon, 01 Aug 2022 16:22:08 +0800</pubDate><description><![CDATA[conf.set("hbase.zookeeper.property.clientPort", "2181"); 这一行的端口写错了]]></description><category></category></item><item><title><![CDATA[在SQL查询语句中，使用条件where 1=2的意义]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/124268410</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/124268410</guid><author>code_aliu</author><pubDate>Tue, 19 Apr 2022 10:56:38 +0800</pubDate><description><![CDATA[有人说where后面跟随的条件1=2为假，所以什么都不做，没有什么作用，其实他真实的作用是为了查询所有的列名，显示所有的列名，所以用假的条件过滤掉所有的值
]]></description><category></category></item><item><title><![CDATA[Maven无外网情况下的依赖导入]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/124006836</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/124006836</guid><author>code_aliu</author><pubDate>Thu, 07 Apr 2022 10:23:40 +0800</pubDate><description><![CDATA[Maven无外网情况下的依赖导入]]></description><category></category></item><item><title><![CDATA[Java Iterator（迭代器）]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123867227</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123867227</guid><author>code_aliu</author><pubDate>Thu, 31 Mar 2022 11:22:26 +0800</pubDate><description><![CDATA[Java Iterator（迭代器）不是一个集合，它是一种用于访问集合的方法，可用于迭代ArrayList和HashSet等集合。

Iterator 是 Java 迭代器最简单的实现，ListIterator 是 Collection API 中的接口， 它扩展了 Iterator 接口。



迭代器 it 的两个基本操作是 next 、hasNext 和 remove。

调用 it.next() 会返回迭代器的下一个元素，并且更新迭代器的状态。

调用 it.hasNext() 用于检测...]]></description><category></category></item><item><title><![CDATA[iptables -F 断开连接-重大问题（会导致服务器挂掉）]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123800905</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123800905</guid><author>code_aliu</author><pubDate>Mon, 28 Mar 2022 17:31:37 +0800</pubDate><description><![CDATA[在linux系统中的服务，可以通过iptables -L 查看系统防火墙能允许那些端口任务通过，往往也会因为一些设置原因造成端口不能进行访问，所以有时候会执行iptables -D的操作，这个时候一定要慎重执行，因为Drop命令执行完全以后就跟iptables -F一样，会删除所有的iptables规则，一旦执行iptables -F就会直接断开跟服务器的连接，因为这条命令删除了各种连接服务器的方式，包括ssh、https、访问服务器数据库、telnet协议连接等等。

解决办法：强制重启服务器，找管理员吧]]></description><category></category></item><item><title><![CDATA[如何查看hive的host（主机地址，端口号）java连接必备]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123714025</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123714025</guid><author>code_aliu</author><pubDate>Thu, 24 Mar 2022 16:12:55 +0800</pubDate><description><![CDATA[1.进入linux安装软件的包下，找到解压后的apache-hive-3.1.0-bin，进入

2.进入conf文件夹下，里面有一个hive-site.xml文件

3.cat hive-site.xml可以查看connection.hosts属性：这里面的value就是主机地址加端口号
]]></description><category></category></item><item><title><![CDATA[HBase客户端连连接--org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123687438</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123687438</guid><author>code_aliu</author><pubDate>Wed, 23 Mar 2022 15:26:48 +0800</pubDate><description><![CDATA[一、错误描述信息：

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Exception in thread "main" org.apac]]></description><category></category></item><item><title><![CDATA[getString()方法用法详解]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123654053</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123654053</guid><author>code_aliu</author><pubDate>Tue, 22 Mar 2022 10:25:38 +0800</pubDate><description><![CDATA[getString()方法用法详解
一、什么是getString
String getString(int columnIndex)throws SQLException：
getString表示以 Java 编程语言中String的形式获取此 ResultSet对象的当前行中指定列的值。  

参数：

columnIndex - 第一个列是 1，第二个列是 2，……

返回：

列值；如果值为 SQL NULL，则返回值为 null

抛出：

SQLException- 如果 columnInd...]]></description><category></category></item><item><title><![CDATA[StringBuilder的用法]]></title><link>https://blog.youkuaiyun.com/code_aliu/article/details/123653752</link><guid>https://blog.youkuaiyun.com/code_aliu/article/details/123653752</guid><author>code_aliu</author><pubDate>Tue, 22 Mar 2022 10:17:04 +0800</pubDate><description><![CDATA[StringBuilder的用法

是一个字符拼接的工具类，它和StringBuffer一样都继承自父类AbstractStringBuilder，在AbstractStringBuilder中使用char[] value字符数组保存字符串，但是没有用final关键字修饰，所以StringBuilder是可变的
...]]></description><category></category></item></channel></rss>